airships

A dirigible usually has gas bags inside a rigid, air-filled structure. So a leak can mix gasses inside the aircraft.

Blimps are big rubber balloons and don't have that hazard.

--

John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

A "dirigible" is any lighter-than-air craft, not necessarily a rigid structure. Early dirigibles certainly weren't. Rigid airships are called "Zeppelins".

Which is what every airship today is. I don't believe anyone is seriously proposing zeppelins, today.

Hydrogen does have a wide range where it is explosive , but it is not explosive over as wide a range as acetylene.

Dan

I did say inflammable and explosive. Acetylene does like being explosive.

--
Bill Sloman, Sydney

hydrogen behaves when it is safely inside the flotation cells of the airshi p, but what happens when some kind of disaster ruptures those cells and the hydrogen is free to mix with air.

When hydrogen is free to mix with air, it rapidly dissipates.

Dan

Any accident that impairs the integrity of the flotation cells is likely to be apparent before the loss of lift can register.

People notice when the structure they are in gets struck by lightning. St. Elmo's fire doesn't count.

--
Bill Sloman, Sydney

Acetylene likes to burn too.

Dan

That's its historical application. From a chemical point of view, it's also an interesting reagent, but a rather dangerous one.

--
Bill Sloman, Sydney

Faster than a flame front?

--

Rick C

If the outer skin of the zeppelin would be air-tight, any leaking hydrogen from hydrogen bags would accumulate at the top of the zeppelin and certainly be a safety issue. Vents in the top of the outer skin should allow the leaking hydrogen to escape from the vehicle.

Sure you can, metal holds it just fine. (It does diffuse slowly through some glasses.) Or put it under the ground.

George H.

It usually dissipates before there is any flame front.

Dan

The WW1 experience with Brits fighting German airships was that they were NOT likely to blow up. The Hindenberg wasn't 'lucky', that event was anomalous. It was, however, caught on film.

Mixing H2 with air is avoidable. Any place that can refill the gas cells would need to know that. We routinely generate, ship, handle acetylene- it's more dangerous than H2.

"Usually" is the key word in that sentence. One "uh-oh" makes up for a whole lot of "atta-boys".

--

Rick C

"Usually" isn't much comfort to those who happen to run into the occasional flame front. "Intrinsically Safe" devices don't store enough energy to sta rt a flame front, and if you design them you find yourself stuck with rathe r small capacitors, even at low supply voltages.

Triboelectric charging is ubiquitous, and accidents can involve a lot of sl iding contact.

--
Bill Sloman, Sydney

Once the British worked out how to put planes in the air close enough to the airships to be able to shoot at them, quite a few of the raiding airships ended up burning and crashing. The Germans went over to heavier-than-air bombers in 1917.

Accidents aren't.

True, but irrelevant.

--
Bill Sloman, Sydney

Shooting wasn't effective until special munitions were developed, that could both penetrate a gas bag and light it off- phosphorous bullets, alternating with explosive ones.

Bullets were enough to make a minor H2 leak, but that wouldn't bring an airship down.

No - "Dirigible" means steerable - as opposed to tethered or free balloons.

No - They were called "rigid airships", the term Zeppelin was reserved for the ships built by the Zeppelin company.

No - There are some which have keels and other stiffening structures.

--
~ Adrian Tuddenham ~ 
(Remove the ".invalid"s and add ".co.uk" to reply) 
www.poppyrecords.co.uk

Even with multiple bullet holes an airship could go on flying for some time. The L6 was hit well over 600 times by rifle fire off Heligoland and still managed to fly safely back to its base in Nordholz.

["Zeppelins Over England" T. v B. Brandenfels - trans: Huntley Patterson (Harrap 1931) pp43-47 ]

--
~ Adrian Tuddenham ~ 
(Remove the ".invalid"s and add ".co.uk" to reply) 
www.poppyrecords.co.uk